Flue gas suppression and environmental evaluation of deodorizer-modified rubber asphalt based on radar method

Abstract

Rubber-modified asphalt (RMA) is associated with impaired storage stability and additional harmful emissions during application. Microwave-oil bath activation of waste rubber powder (WRP) to improve its compatibility with asphalt. The treatment of VOCs and malodorous gas emissions from RMA is carried out using powder deodorizers, liquid deodorizers and their combination. The storage stability, high and low temp rheological behavior of RMA were investigated. The effects and machinations of three deodorants on odor removal and VOCs inhibition of RMA were explored. The emission indexes based on the characteristic pollutants of VOCs and malodorous gases were proposed to conduct a comprehensive environmental impact assessment by the Radar method. The results show that the activated WRP has a fluffier morphology and is better encapsulated by the oil film, which enhances the storage stability of RMA. The incorporation of deodorant has not altered the viscoelastic properties of asphalt. The higher specific surfaced areas and extensive pore structures was contributed to the adsorption of VOCs molecules from asphalt. VOCs and odor gases from asphalt could be inhibited by liquid deodorizers based on Lewis acid-base reactions, addition reactions, catalytic reactions, and redox reactions. LMA was the most effective in decreasing odorant gases, with reductions of up to 92.6% and 90.8% for isobutanol and dimethyl disulfide, respectively. PMA had the optimal inhibitory activity for vinyl chloride, which was 67.7%. The decrease of total concentration of VOCs in RMA by PMA (powder deodorant-modified asphalt), LMA (liquid deodorant-modified asphalt), and CMA (complex deodorant-modified asphalt) could be calculated as 51.7%, 34.1% and 46.7% respectively. RMA had a high load on the environment, and the overall advantage of CMA was greater. The environmental impacts of the four modified asphalts were ranked as CMA < PMA < LMA < RMA. Therefore, the utilization of powder and liquid compounding was recommended to improve the environmental impact of RMA.